CN102517511B - Steel for high-expansion-rate petroleum casing and method for manufacturing petroleum casing - Google Patents

Abstract

The invention discloses steel for a high-expansion-rate petroleum casing and a method for manufacturing the petroleum casing, which relates to an iron-based alloy. The petroleum casing consists of the raw material elements in percentage by mass: 0.03-0.25 percent of C, 0.3-2.5 percent of Si, 0.5-4.0 percent of Mn, 0-0.5 percent of Cr, less than or equal to 0.02 percent of S, less than or equal to 0.02 percent of P and the balance of Fe; one, two or three of 0.01-0.12 percent by mass of Nb, 0.01-0.06 percent by mass of Ti and 0.01-0.12 percent by mass of V can be added; a steel pipe blank or a steel plate is manufactured by smelting; and a high-expansion-rate seamless petroleum casing is manufacturing with the steel pipe blank by using a seamless pipe molding technology and a high-expansion-rate seamed petroleum casing is manufactured by adopting straight slit resistance welding with the steel plate. The expansion rate of the manufactured petroleum casing is more than or equal to 30 percent, and the defects of low expansion rate and high cost of the conventional expandable casing for an oil-gas well are overcome.

Description

Steel for high expansion rate oil casing and method for making oil casing

technical field

The technical solution of the invention relates to iron-based alloys, specifically steel for high-expansion oil casings and a method for making oil casings.

Background technique

Nowadays, the oil casing is lowered into the well using a step-by-step downward extension technology. The next-level casing passes through the upper-level casing, resulting in a smaller and smaller casing diameter. The expansion tube technology is to run the casing into the predetermined position in the well, transport the mud fluid through the middle pipe, and fill the gap space outside the casing, and then the expansion cone at the lower part is pushed by the liquid pressure to expand and expand the casing from bottom to top, so that A new technology of drilling, completion and workover in which the diameter of the casing is deformed to be close to the well wall. Applying this technology can realize single well diameter in deep wells, ultra-deep wells and harsh geological conditions, providing a new way to solve deep oil and gas exploitation. At present, the key to restricting the development of single-caliber technology is to prepare large-diameter and expandable oil casings, and the key point is to provide new alloy steel materials for this oil casing.

In the prior art, CN101812631A discloses steel for oil well expandable casing and its manufacturing method. The mass percentages of the components of the steel alloy material for oil well expandable casing are: C: 0.08-0.2%, Mn: 1-2%, Si : 0.15～0.35%, Al: 0.02～0.06%, P≤0.01%, S≤0.005%, N≤0.008%, Ca: 0.001～0.005%, and the balance is Fe. In order to ensure the performance of this material, the manufactured steel pipe It is necessary to carry out isothermal treatment in the F+A two-phase region at 730-790°C, and then isothermally at 350-450°C for a certain period of time to obtain the metallographic microstructure of F+carbon-free B+residual A. Although the pipe with the above steel alloy material composition can utilize the phase transformation induced plastic effect during expansion, the deformation rate of the expandable pipe is only 15%. In addition, because the casing has a length of 8-10m, heating in the F+A two-phase region at 730-790°C and isothermal heat treatment at 350-450°C are not only complicated in process, but also difficult to control in large-scale production. The cost is very high; CN101194038A discloses an oil well pipe for expansion pipe and its manufacturing method. The oil well pipe for expansion pipe contains C: 0.03-0.14%, Si<0.8%, Mn: 0.3-2.5%, P <0.03%, S<0.01%, Ti: 0.005-0.03%, Al<0.1%, N: 0.001-0.01%, B: 0.0005-0.003%; Nb, Ni, Mo, Cr, Cu, One or more of V, and if necessary, contain one or two of Ca and REM, and satisfy A=2.7C+0.4Si+Mn+0.45Ni+0.45Cu+0.8Cr+2Mo ≥1.8, the balance is composed of iron and unavoidable impurities, combined with quenching above Ac3+30°C and tempering at 350-720°C to obtain tempered martensite structure, the expansion of pipes with the above element components The tube rate is only 20%. In addition, compared with CN101812631A, alloy elements such as Ni, Mo, and Cu are added to the alloy composition of the pipe, and the cost of the alloy steel is greatly increased.

In conclusion, the existing expandable casings for oil and gas wells still have the disadvantages of low actual expandability and high cost.

Contents of the invention

The technical problem to be solved by the present invention is to provide steel for high expansion rate oil casing and its method for making oil casing. The expansion rate of the oil casing made of this steel is ≥ 30%. After deformation and strengthening, the yield strength of the pipe reaches 550-1000MPa, the tensile strength reaches 800-1300MPa and the elongation rate is ≥10%, which overcomes the problems of low actual expansion rate and high production cost of the existing expandable casing for oil and gas wells. shortcoming.

The technical solution adopted by the present invention to solve the technical problem is: steel for high expansion rate oil casing, the raw materials of which are composed of elements in terms of mass percentage: C: 0.03-0.25%, Si: 0.3-2.5%, Mn: 0.5-4.0 %, Cr: 0 to 0.5%, S: ≤0.02%, P: ≤0.02%, and Fe: the balance, which are smelted and made into steel billets or steel plates.

For the above-mentioned high expansion rate oil casing steel, one, two or three of Nb, Ti and V are added to the elemental raw material composition, and the addition amount is calculated by mass percentage: Nb: 0.01-0.12%, Ti : 0.01 to 0.06%, V: 0.01 to 0.12%.

The above-mentioned high-expansion oil casing steel, whose elemental raw materials are commercially purchased, is smelted and made into a steel billet or steel plate, which is a well-known prior art.

The method for making the above-mentioned high-expansion oil casing steel for oil casing includes a method for manufacturing a high-expansion seamless oil casing and a method for manufacturing a high-expansion seamed oil casing. The steps are as follows:

A. The production method of high expansion rate seamless oil casing pipe: the above-mentioned element composition raw materials are smelted and made into high expansion rate oil casing steel for steel pipe blanks, and seamless steel pipes are made by seamless pipe forming technology. Control the temperature of the seamless steel pipe to 800-900°C, and then use forced air cooling to rapidly cool the temperature of the seamless steel pipe to room temperature to obtain a high-expansion seamless oil with F+M or B+a small amount of residual A complex phase structure. Casing, the yield strength of the obtained high-expansion seamless oil casing pipe reaches 350-450 MPa, the tensile strength reaches 640-750 MPa, and the elongation is ≥ 30%; the high-expansion seamless oil casing pipe is subjected to hole expansion deformation , expansion rate ≥ 30%, after 30-50% expansion deformation strengthening, the yield strength of the high expansion rate seamless oil casing pipe is 550-1000MPa, tensile strength is 800-1300MPa and elongation ≥ 10%.

B. Manufacturing method of oil casing with high expansion rate seam: smelting the above-mentioned elements by mass percentage as raw materials and making steel plate for high expansion rate oil casing pipe, using straight seam resistance welding manufacturing technology to make the steel plate into a seam Seam steel pipe, and then conduct heat treatment. The heat treatment method is to use a medium frequency induction heater to heat to 800-900°C, and then use water cooling or forced air to quickly cool the seam steel pipe to room temperature to obtain a small amount of F+M or B+. The high-expansion slotted petroleum casing of the multi-phase structure of residual A, the yield strength of the obtained high-expansion slotted petroleum casing pipe reaches 350-450MPa, the tensile strength reaches 640-750MPa, and the elongation is ≥ 30%; The high expansion rate slotted oil casing pipe is subjected to hole expansion deformation, the expansion rate is ≥ 30%, and after being strengthened by 30-50% expansion deformation, the yield strength of the high expansion rate slotted oil casing pipe is 550-1000MPa, tensile strength Strength 800 ~ 1300MPa and elongation ≥ 10%.

The above-mentioned high-expansion oil casing steel is used in the method for manufacturing an oil casing, and the outer diameter of the prepared oil casing is 110mm-339mm and the wall thickness is 6mm-14mm.

The metallurgical equipment and processes involved in the method for making the oil casing with high expansion rate oil casing steel are well known in the technical field.

The above-mentioned high-expansion oil casing steel is not limited to be used in the preparation of oil casing, and can also be used to make other machine parts.

The beneficial effects of the present invention are: compared with the existing oil well expandable casing steel and its manufacturing method, the present invention's high-expansion oil casing steel and its method for making petroleum casing are significantly improved in that:

(1) The expansion rate of the oil casing pipe made of the high expansion rate oil casing pipe steel of the present invention is ≥ 30%, which is higher than 15% to 20% of the prior art. The high expansion rate oil casing pipe has F+M or B+ a small amount of residual A metallographic microstructure, which has the characteristics of low yield strength and high deformation strengthening rate, and its yield strength is 350-450MPa, and its tensile strength is 640-750MPa , elongation ≥ 30%, after 30-50% expansion and deformation strengthening, the yield strength of the high-expansion oil casing pipe is 550-1000MPa, tensile strength 800-1300MPa and elongation ≥ 10%. The following examples and figures give concrete demonstration of the remarkable advances of the present invention.

(2) The raw materials for preparing the high-expansion petroleum casing steel of the present invention are easily available in the market, and the cost is relatively low, which reduces the overall production cost of the high-expansion petroleum casing.

(3) The method for producing the oil casing with the high-expansion oil casing steel of the present invention is easy to operate and easy to be popularized and applied in industry.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is the physical photograph of the part before and after 50% expansion deformation in the high expansion rate seamless petroleum casing produced in Example 4.

Detailed ways

Example 1

High-expansion oil casing steel, the element composition raw materials are: 0.07%C, 2.0%Si, 1.2%Mn, ≤0.02%S, ≤0.02%P and the balance is Fe, and the raw materials are smelted and made steel plate.

The above-mentioned high-expansion petroleum casing steel that has been smelted and made into a steel plate is made into a seamed steel pipe by using the straight seam resistance welding manufacturing technology, and then heat-treated. The heat treatment method is to use a medium-frequency induction heater to heat to 900°C, and then use water cooling or forced air to quickly cool the seamed steel pipe to room temperature, and obtain a high-expansion seamed oil with a multiphase structure of F+M or B+a small amount of residual A. The outer diameter is 110mm and the wall thickness is 6mm. Casing, the yield strength of the obtained high-expansion slotted petroleum casing pipe reaches 380MPa, the tensile strength reaches 690MPa, and the elongation rate is 32%; The outer diameter of the pipe is 145mm, and the expansion rate is 32%. After strengthening through 32% expansion deformation, the yield strength of the high expansion rate slotted oil casing pipe is 650MPa, the tensile strength is 880MPa and the elongation is 19%.

Example 2

High expansion rate oil casing steel, its elemental composition raw materials are calculated by mass percentage: 0.15%C, 1.5%Si, 1.5%Mn, 0.5%Cr, 0.05%Nb, ≤0.02%S, ≤0.02%P and the balance It is Fe, which is smelted and made into steel billets.

The above-mentioned high-expansion petroleum casing steel that has been smelted and made into steel pipe blanks is made into seamless steel pipes by using seamless pipe forming technology. Cool to room temperature to obtain a high expansion rate seamless oil casing with an outer diameter of 110 mm and a wall thickness of 6 mm with F+M or B+ a small amount of residual A multiphase structure, and the yield strength of the obtained high expansion rate seamless oil casing pipe The tensile strength reaches 400MPa, the tensile strength reaches 700MPa, and the elongation rate is 30%. The high expansion rate seamless oil casing pipe is reamed and deformed. After reaming, the outer diameter of the expanded pipe is 154mm, and the expansion rate is 40%. After % expansion deformation strengthening, the yield strength of the high expansion rate seamless oil casing pipe is 700MPa, the tensile strength is 1100MPa and the elongation is 16%.

Example 3

High expansion rate oil casing steel, its elemental composition raw materials are calculated by mass percentage: 0.2%C, 2.5%Si, 3.5%Mn, 0.02%Ti, 0.25%Cr, ≤0.02%S, ≤0.02%P and the balance It is Fe, which is smelted and made into steel billets.

The above-mentioned high-expansion oil casing steel that has been smelted and made into steel pipe blanks is made into seamless steel pipes by seamless pipe forming technology. The temperature of the seamless steel pipes is controlled at 800 °C, and then forced air cooling is used to make the temperature of the steel pipes rapidly Cool to room temperature to obtain a high expansion rate seamless oil casing with an outer diameter of 219 mm and a wall thickness of 9 mm with F+M or B+ a small amount of residual A multiphase structure, and the yield strength of the obtained high expansion rate seamless oil casing pipe The tensile strength reaches 450MPa, the tensile strength reaches 750MPa, and the elongation rate is 30%. The high expansion rate seamless oil casing pipe is reamed and deformed. After reaming, the outer diameter of the expanded pipe is 285mm, and the expansion rate is 30%. After % expansion deformation strengthening, the yield strength of the high expansion rate seamless oil casing pipe is 1000 MPa, the tensile strength is 1300 MPa and the elongation is 11%.

Example 4

High expansion rate oil casing steel, its elemental composition raw materials are calculated by mass percentage: 0.17%C, 1.9%Si, 3.0%Mn, 0.1%Cr, 0.1%V, ≤0.02%S, ≤0.02%P and the balance It is Fe, which is smelted and made into steel billets.

The above-mentioned high-expansion oil casing steel that has been smelted and made into steel pipe billets is made into seamless steel pipes by seamless pipe forming technology. Cool to room temperature to obtain a high expansion rate seamless oil casing with an outer diameter of 219 mm and a wall thickness of 12 mm with F+M or B+ a small amount of residual A multiphase structure, and the yield strength of the obtained high expansion rate seamless oil casing pipe The tensile strength reaches 380MPa, the tensile strength reaches 700MPa, and the elongation rate is 30%. The high expansion rate seamless oil casing pipe is reamed and deformed. After reaming, the outer diameter of the expanded pipe is 329mm, and the expansion rate is 50%. After % expansion deformation strengthening, the yield strength of the high expansion rate seamless oil casing pipe is 850 MPa, the tensile strength is 1250 MPa and the elongation is 14%.

Fig. 1 is the physical photograph of the parts before and after 50% expansion and deformation of the high-expansion seamless oil casing pipe produced in this embodiment. The high-expansion seamless petroleum casing produced by the embodiment has good deformation performance and good surface quality.

Example 5

High expansion rate oil casing steel, its element composition raw materials are calculated by mass percentage: 0.03%C, 2.5%Si, 0.5%Mn, 0.5%Cr, 0.1%V, ≤0.02%S, ≤0.02%P and the balance It is Fe, which is smelted and made into steel billets.

The above-mentioned high-expansion petroleum casing steel that has been smelted and made into steel pipe blanks is made into seamless steel pipes by seamless pipe forming technology. Cool to room temperature to obtain a high expansion rate seamless oil casing with an outer diameter of 110 mm and a wall thickness of 6 mm with F+M or B+ a small amount of residual A multiphase structure, and the yield strength of the obtained high expansion rate seamless oil casing pipe The tensile strength reaches 360MPa, the tensile strength reaches 650MPa, and the elongation rate is 35%. The high expansion rate seamless oil casing pipe is reamed and deformed. After reaming, the outer diameter of the expanded pipe is 143mm, and the expansion rate is 30%. After % expansion deformation strengthening, the yield strength of the high expansion rate seamless oil casing pipe is 550 MPa, the tensile strength is 810 MPa and the elongation is 15%.

Example 6

High expansion rate oil casing steel, its elemental composition raw materials are calculated by mass percentage: 0.25%C, 0.3%Si, 4.0%Mn, 0.01%Cr, 0.01%Nb, 0.01%Ti, ≤0.02%S, ≤0.02% P and the balance are Fe, which are smelted and made into steel billets.

The above-mentioned high-expansion oil casing steel that has been smelted and made into steel pipe blanks is made into seamless steel pipes by seamless pipe forming technology. The temperature of the seamless steel pipes is controlled at 800 °C, and then forced air cooling is used to make the temperature of the steel pipes rapidly Cool to room temperature to obtain a high expansion rate seamless oil casing with an outer diameter of 339 mm and a wall thickness of 14 mm with F+M or B+ a small amount of residual A multiphase structure, and the yield strength of the obtained high expansion rate seamless oil casing pipe The tensile strength reaches 430MPa, the tensile strength reaches 750MPa, and the elongation rate is 30%. The high expansion rate seamless oil casing pipe is reamed and deformed. After reaming, the outer diameter of the expanded pipe is 442mm, and the expansion rate is 30%. After % expansion deformation strengthening, the yield strength of the high expansion rate seamless oil casing pipe is 900 MPa, the tensile strength is 1150 MPa and the elongation is 10%.

Example 7

High expansion rate oil casing steel, its element composition raw materials are calculated by mass percentage: 0.09%C, 1.5%Si, 0.5%Mn, 0.1%Cr, 0.12%Nb, 0.12%V, ≤0.02%S, ≤0.02% P and the balance are Fe, which are smelted and made into steel billets.

The above-mentioned high-expansion oil casing steel that has been smelted and made into steel pipe blanks is made into seamless steel pipes by seamless pipe forming technology. The temperature of the seamless steel pipes is controlled at 800 °C, and then forced air cooling is used to make the temperature of the steel pipes rapidly Cool to room temperature to obtain a high expansion rate seamless oil casing with an outer diameter of 339 mm and a wall thickness of 14 mm with F+M or B+ a small amount of residual A multiphase structure, and the yield strength of the obtained high expansion rate seamless oil casing pipe The tensile strength reaches 420MPa, the tensile strength reaches 750MPa, and the elongation rate is 33%. The high expansion rate seamless oil casing pipe is reamed and deformed. After reaming, the outer diameter of the expanded pipe is 475mm, and the expansion rate is 40%. After % expansion deformation strengthening, the yield strength of the high expansion rate seamless oil casing pipe is 870 MPa, the tensile strength is 1200 MPa and the elongation is 15%.

Example 8

High expansion rate oil casing steel, its elemental composition raw materials are calculated by mass percentage: 0.07%C, 2.0%Si, 2.0%Mn, 0.1%Cr, 0.03%Ti, 0.05%V, ≤0.02%S, ≤0.02% P and the balance are Fe, which are smelted and made into steel plates.

The above-mentioned high-expansion petroleum casing steel that has been smelted and made into a steel plate is made into a seamed steel pipe by using the straight seam resistance welding manufacturing technology, and then heat-treated. The heat treatment method is to use a medium-frequency induction heater to heat to 850°C, and then use water cooling or forced air to rapidly cool the seamed steel pipe to room temperature to obtain a high-expansion seamed oil with a multiphase structure of F+M or B+a small amount of residual A. The outer diameter is 339mm and the wall thickness is 14mm. The casing has a yield strength of 350MPa, a tensile strength of 640MPa, and an elongation of 35%. The seamed pipe is reamed and deformed. After reaming, the outer diameter of the expanded pipe is 442mm, and the expansion rate is 30%. Through 30% expansion deformation After strengthening, the yield strength of the seamed pipe is 550MPa, the tensile strength is 800MPa and the elongation is 15%.

Example 9

High expansion rate oil casing steel, its elemental composition raw materials are calculated by mass percentage: 0.19%C, 2.5%Si, 0.5%Mn, 0.05%Nb, 0.06%Ti, 0.05%V, ≤0.02%S, ≤0.02% P and the balance are Fe, which are smelted and made into steel billets.

The above-mentioned high-expansion petroleum casing steel that has been smelted and made into steel pipe blanks is made into seamless steel pipes by using seamless pipe forming technology. Cool to room temperature to obtain a high expansion rate seamless oil casing with an outer diameter of 219 mm and a wall thickness of 12 mm with F+M or B+ a small amount of residual A multiphase structure, and the yield strength of the obtained high expansion rate seamless oil casing pipe The tensile strength reaches 400MPa, the tensile strength reaches 750MPa, and the elongation rate is 33%. The high expansion rate seamless oil casing pipe is reamed and deformed. After reaming, the outer diameter of the expanded pipe is 306mm, and the expansion rate is 40%. After % expansion deformation strengthening, the yield strength of the high expansion rate seamless oil casing pipe is 900 MPa, the tensile strength is 1200 MPa and the elongation is 11%.

Example 10

High expansion rate oil casing steel, its elemental composition raw materials are calculated by mass percentage: 0.03%C, 2.5%Si, 0.5%Mn, 0.5%Cr, ≤0.02%S, ≤0.02%P and Fe: the balance, after Smelted and made into steel billets.

The above-mentioned high-expansion petroleum casing steel that has been smelted and made into steel pipe blanks is made into seamless steel pipes by seamless pipe forming technology. Cool to room temperature to obtain a high expansion rate seamless oil casing with an outer diameter of 110 mm and a wall thickness of 6 mm with F+M or B+ a small amount of residual A multiphase structure, and the yield strength of the obtained high expansion rate seamless oil casing pipe The tensile strength reaches 360MPa, the tensile strength reaches 650MPa, and the elongation rate is 32%. The high expansion rate seamless oil casing pipe is reamed and deformed. After reaming, the outer diameter of the expanded pipe is 143mm, and the expansion rate is 30%. After % expansion deformation strengthening, the yield strength of the high expansion rate seamless oil casing pipe is 600MPa, the tensile strength is 820MPa and the elongation is 19%.

Example 11

High expansion rate oil casing steel, its elemental composition raw materials are calculated by mass percentage: 0.25%C, 0.3%Si, 4.0%Mn, 0.25%Cr, ≤0.02%S, ≤0.02%P and Fe: the balance, after Smelted and made into steel plates.

The above-mentioned high-expansion petroleum casing steel that has been smelted and made into a steel plate is made into a seamed steel pipe by using the straight seam resistance welding manufacturing technology, and then heat-treated. The heat treatment method is to use a medium-frequency induction heater to heat to 800°C, and then use water cooling or forced air to quickly cool the seamed steel pipe to room temperature, and obtain a high-expansion seamed oil with a multiphase structure of F+M or B+a small amount of residual A. The outer diameter is 245mm and the wall thickness is 9mm. Casing, the yield strength of the obtained high-expansion slotted petroleum casing pipe reaches 450MPa, the tensile strength reaches 750MPa, and the elongation rate is 30%; The outer diameter of the pipe is 319mm, and the expansion rate is 30%. After strengthening through 30% expansion deformation, the yield strength of the high expansion rate slotted oil casing pipe is 900MPa, the tensile strength is 1100MPa and the elongation is 12%.

Claims (3)

1. The method for producing oil casing with steel for high expansion rate oil casing, characterized in that: the element composition raw materials of steel for high expansion rate oil casing are calculated by mass percentage: C: 0.03-0.25%, Si: 0.3- 2.5%, Mn: 0.5-4.0%, Cr: 0-0.5%, S: ≤0.02%, P: ≤0.02%, and Fe: balance, including the production method and high expansion rate of seamless oil casing with high expansion rate The manufacturing method of the seamed oil casing, the steps are as follows: A. The production method of high expansion rate seamless oil casing pipe: smelting the raw materials of the above-mentioned mass percentage elements to make steel for high expansion rate oil casing pipe of steel billet, and adopting seamless pipe forming technology to make seamless steel pipe , control the temperature of the seamless steel pipe at 800-900°C, and then use forced air cooling to rapidly cool the temperature of the seamless steel pipe to room temperature, and obtain a high-expansion ratio-free structure with F + M or B + a small amount of residual A complex phase structure. The yield strength of the obtained high-expansion seamless oil casing pipe reaches 350-450MPa, the tensile strength reaches 640-750MPa, and the elongation rate is ≥ 30%. The high-expansion seamless oil casing pipe is expanded. Hole deformation, expansion rate ≥ 30%, after 30-50% expansion deformation strengthening, the yield strength of the high expansion rate seamless oil casing pipe is 550-1000MPa, tensile strength is 800-1300MPa and elongation ≥ 10% ; B. Manufacturing method of seamed oil casing with high expansion rate: smelting the raw materials of the above-mentioned elements by mass percentage and making steel plate for high expansion rate oil casing pipe, using straight seam resistance welding manufacturing technology to make the steel plate The seamed steel pipe is then subjected to heat treatment. The method of heat treatment is to use an intermediate frequency induction heater to heat it to 800-900°C, and then use water cooling or forced air to quickly cool the seamed steel pipe to room temperature to obtain F + M or B + High expansion rate slotted oil casing pipe with a small amount of residual A multiphase structure, the yield strength of the obtained high expansion rate slotted oil casing pipe reaches 350-450MPa, the tensile strength reaches 640-750MPa, and the elongation rate is ≥30%; The high expansion rate slotted oil casing pipe is subjected to hole expansion deformation, the expansion rate is ≥ 30%, and after being strengthened by 30-50% expansion deformation, the yield strength of the high expansion rate slotted oil casing pipe is 550-1000MPa, Tensile strength 800 ~ 1300MPa and elongation ≥ 10%. 2. The method for producing petroleum casing with the high expansion rate oil casing steel according to claim 1, characterized in that: Nb, Ti and V are added to the element composition raw materials of the high expansion rate oil casing steel. One, two or three of them are added in the following mass percentages: Nb: 0.01-0.12%, Ti: 0.01-0.06%, V: 0.01-0.12%. 3. According to claim 1, the method for making oil casing with high expansion rate steel for oil casing, characterized in that: the outer diameter of the prepared oil casing is 110mm-339mm and the wall thickness is 6mm ~14mm.